[Basic studies on glass ceramics. 3. Influence on calcification of osteogenic cells in vitro]

Two established osteogenic cell lines (NY, MC 3 T3-E 1) were used in vitro to determine the biocompatibility of glass ceramics and their effect on initial calcification of osteogenic cells. Morphological study of the cell under the phase-contrast microscopy and histochemical staining were applied as follows. First, glass ceramic granules were placed in 60 mm dishes, and cells were suspended in the dishes in alpha-MEM supplemented with 10% FBS (basic medium) or medium with 50 micrograms/ml of L-ascorbic acid added. After 8 or 14 day of culturing, calcium formation was tested by von-Kossa's staining. Also, alkaline phosphatase staining was performed by the azo-dye method. As controls, cultures in dishes without glass ceramic granules were stained at the same time. The results obtained in the experimental culture were as follows. 1. Phase contrast microscopy showed that contacts with glass ceramics did not cause cellular death or degeneration. 2. In both cell cultures with the glass ceramics the von-Kossa reaction was positive as early as the 8th day. 3. The alkaline phosphatase reaction on the 8th day occurred only in MC 3 T3-E 1. The reaction was localized on fibroblastic cells which proliferated three-dimensionally around glass ceramics, and on small polyhedral cells situated relatively for apart from the ceramics. 4. On the 14th day, the MC 3 T 3-E 1 formed large nodules around the glass ceramics, and they were stained uniformly positive by von-Kossa's method. The alkaline phosphatase-positive cells extended spoke-like forms. 5. In medium with L-ascorbic acid, growth of NY was inhibited, After being cultured for 14 days, abundant von-Kossa positive reaction was found around glass ceramics in both cells. In MC 3 T 3-E1 on the 8th days, the alkaline phosphatase reaction was stronger with glass ceramics than with basic medium only. On the contrary, in the control cultures of both cells there was negative von-Kossa reaction during the culture period. The above results showed that glass ceramic granules have the biocompatibility needed for bone grafts, and they facilitated calcification of MC 3 T 3-E 1 in culture.